Method For Optical Chassis Measurement

Abstract

The invention relates to a method for optically measuring a chassis at a testing station. According to said method, radiation that is reflected by several optically distinguishable characteristic structures on a vehicle, comprising at least one wheel and a surrounding bodywork section, is detected by a measuring device with the aid of an image capture unit and at least the wheel plane and the wheel centre point are determined by an evaluation of the positional data obtained by means of the detected radiation. To obtain reliable measurement results relatively simply, several planes are projected at least onto the wheel ( 5 ) and the surrounding bodywork using structured light that is emitted by at least one radiation source of the measuring device, and the intersection of the planes with the wheel ( 5 ) and the surrounding bodywork or with a sub-section of the wheel and bodywork is captured as profile lines (3D point cloud) by means of at least one image capture unit, on the basis of a known geometrical assignment of the radiation source or sources to the image capture unit or units. From the intersection points of the profile lines with e.g. the edge of the rim or other rotationally symmetrical contours on the wheel and the wheel opening, the spatial position of characteristic surface points is determined, said points being used to directly determine the relevant chassis data.

1 . A method for optical chassis measurement at a testing station in which, out of a plurality of optically differentiable characteristic structures on a vehicle, radiation reflected against at least one wheel and a surrounding chassis opening is detected by a measuring device by means of an image capture device and, through evaluation of position data acquired from the detected radiation, at least the wheel plane and the wheel center point are determined, wherein a plurality of planes ( 12 ,  12 ′) of structured light emitted by a radiation source of the measuring device are projected against at least the wheel ( 5 ) and the surrounding chassis, and the intersections of the planes ( 12 ) with the wheel ( 5 ) and the surrounding chassis or a subregion thereof are recorded in the form of profile lines ( 14 ,  14 ′) by means of at least one image capture device and on the basis of the geometrically known association of the at least one radiation source and the at least one image capture device; and where applicable, based on intersecting points of the profile lines ( 14 ,  14 ′) and the wheel rim edge or other rotationally symmetrical contours on the wheel and also based on the wheel opening of the chassis, the spatial position of characteristic surface points are determined as position data, based on which the chassis data of interest are then determined. 
   
   
       2 . The method as recited in  claim 1 , wherein through the projection of the planes, specific individual profiles or the entire surface structure of the object sections of interest, at least of the wheel ( 5 ) and of the chassis opening, are recorded. 
   
   
       3 . The method as recited in  claim 1  or  2 , wherein a light-section method, a gray code method with an encoded light setup, or a phase-shift method is used. 
   
   
       4 . The method as recited in one of the preceding claims, wherein in order to determine the wheel plane, the wheel center point, and, where applicable, the chassis opening around the wheel, a multitude of surface points in the form of a 3-D aggregate of points are consulted, but at least three intersecting points between two surface profiles and rotationally symmetrical contours of the wheel are used. 
   
   
       5 . The method as recited in one of the preceding claims, wherein the load state of the wheel is determined based on the edge of the wheel opening, while the track and camber are determined based on the wheel plane and wheel center point. 
   
   
       6 . The method as recited in one of the preceding claims, wherein in the scanning, significant surface features on the wheel such as the valve, hole pattern, and labeling as well as dirt and/or a damaged region are detected and based on these surface features, a wheel rim eccentricity is detected when the wheel is rotating and taken into account in subsequent evaluation. 
   
   
       7 . The method as recited in one of the preceding claims, wherein the measurement is carried out as the vehicle is driven past and travel direction data are acquired based on a detection of the movement direction of chassis surface structures.